1. Field of the Invention
The present invention relates generally to access networks, such as wireless local area networks (WLANs) and, more specifically, to a mechanism for optimizing a process of selecting one or more intermediary networks through which a roaming user is authenticated with his home network while using Extensible Authentication Protocol (EAP).
2. Description of the Related Art
The term “wireless local area networking” (WLAN) generally refers to the use of a local area network (LAN) in which data is transmitted by radio communication between the user's terminal (e.g., wireless-enabled laptop computer, handheld PDA, etc.) and a nearby device known as an access point. The access point, in turn, is part of a computer network known as an access network, and the user can transparently access computers or other devices connected to the network from the user's terminal, as though the user's device were connected to the network via a wired connection.
A WLAN interworking architecture developed by the Third-Generation Partnership Program (3GPP), a consortium of telecommunications standards bodies operating under a collaboration agreement, provides an architecture in which a user's terminal can connect via a WLAN to a remote data network; such as the Internet or a core network of cellular telecommunication systems. The mechanism as it applies to cellular telecommunication operators inter-working with WLANs is defined in 3GPP's Release 6 documents, TS 23.234 and TS 24.234.
“Public WLAN” is a term that generally refers to the placement of access points in publicly accessible areas, such as airport lounges, waiting rooms, and coffeehouses, giving rise to areas known as “hotspots” in which users can access remote networks to check e-mail, surf the Internet, upload and download files, and so forth. Accessing the Internet using public access WLAN can be considered an alternative to accessing it using third-generation (“3G”) high-bandwidth cellular data service. Indeed, it has been suggested that terminals be capable of roaming between 3G and WLAN and be able to access 3G services via WLAN. Accordingly, it has been suggested that charges for accessing the WLAN services be charged to the user's cellular service provider bill.
To the public access WLAN operator (i.e., hotspot operator), billing or accounting is one of the most important aspects of the overall process known as authentication, authorization and accounting (AAA). The user's home network (HN), such as a cellular telecommunication services provider with which the user has a subscription agreement, includes an AAA server that performs the AAA function in conjunction with an AAA proxy server that is part of the access network. The authentication process involves routing AAA information to the HN's AAA server. Because all public WLAN operators may not have roaming agreements directly with the operator of the user's HN, routing in such cases must occur via one or more intermediary networks or brokers, whose operators have roaming agreements with the WLAN operator, the user's HN operator, or other intermediary network operators.
The Internet Engineering Task Force (IETF), an open consortium of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet, has defined a protocol known as Extensible Authentication Protocol (EAP) that provides an authentication framework supporting multiple authentication methods. EAP can be used by various access network technologies, including WLAN technology.
One difficulty in the authentication process is selecting the intermediary network(s) through which to route the AAA information. In the most common authentication schemes, the user's terminal plays a primary role in the selection of intermediary networks. 3GPP has suggested the use of EAP to have the WLAN provide or “advertise” information or “hints” to the user's terminal to aid the terminal in selecting one or more intermediary network(s) through which to route the AAA information. The information can be, for example, a list of WLAN operators' roaming partners, i.e., intermediary operators with whom the WLAN operator has a roaming agreement. 3GPP's suggestion includes that the terminal indicate the selected routing by inserting information into or “decorating” a Network Access Identifier (NAI) and transmitting it to the WLAN.
The above-described EAP-based IETF method is limited by the capacity of the EAP Request/Identity packet that the WLAN would transmit to the terminal (as well as the fact that EAP messages cannot be fragmented). It has been estimated that a selection of as many as about 50 roaming partners could be advertised in this manner without exceeding the limitations of the protocols involved. With the worldwide increase in public access WLAN operators, however, potential intermediary operators may number in the hundreds. Clearly, it would be impractical to advertise this many potential intermediary operators, even if a higher-capacity alternative to EAP existed. Even the advertisement of only 50 roaming partners may not be considered an appropriate use of airlink resources by the access network operator, who may prefer to advertise far fewer roaming partners than the maximum possible.
Accordingly, it can be seen that a need remains in the art for a system and method for selecting a limited set of potential intermediary operators to advertise to a user's terminal. It is to such a system and method that the present invention is primarily directed.